There's a support document on Apple's site detailing how to replace the hard drive. The bottom-plate screws have to be reinstalled in a particular order (think of torquing down the head on an internal combustion engine).

There's a support document on Apple's site detailing how to replace the hard drive. The bottom-plate screws have to be reinstalled in a particular order (think of torquing down the head on an internal combustion engine).